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Varicella (chicken pox) vaccine

How are children protected against chicken pox?

Vaccines or needles are the best way to protect children against some very serious infections. The National Advisory Committee on Immunization (NACI) strongly recommends routine immunization.

The varicella (chicken pox) vaccine is given to children after their first birthday. It will protect them from this common childhood disease and its potential for serious complications, such as bacterial skin infections.

What is chicken pox?

Chicken pox is caused by the varicella-zoster virus.

About 90 per cent of chicken pox cases occur before the child becomes 12 years of age.

Children with chicken pox will feel flu-like symptoms such as fatigue, mild headache, fever up to 39°C (102°F), chills and muscle or joint aches a day or two before the itchy, red rash appears.

The rash appears anywhere on the body as raised red blisters that are extremely itchy. Some children have only a few blisters while others can have as many as 500.

The child will be most infectious (contagious) from one to two days before the rash appears. These blisters dry up and form scabs in four to five days.

How do you get chicken pox?

Chicken pox is extremely contagious. It spreads very quickly from person to person. The most common way the infection is spread is through the air if someone with chicken pox coughs or sneezes. You can also get chicken pox if you touch a blister or the liquid from a blister.

A pregnant woman with chicken pox can pass it on to her unborn baby before birth. Mothers with chicken pox can also give it to their newborn baby after birth.

Why is the varicella vaccine important?

In about five to 10 per cent of healthy children, chicken pox infection can lead to more serious problems such as :

  • bacterial skin infections and/or necrotizing
  • fasciitis ("flesh-eating disease")
  • pneumonia (infection of the lungs)
  • encephalitis (infection of the brain)
  • infection of other sites (e.g., blood)
  • birth defects may occur if the baby gets chicken pox from their mothers before they are born.

Chicken pox can be very severe or even lifethreatening to newborn babies, and anyone with a weak immune system.

The vaccine is recommended for children 12 months of age and older because, until then, babies have maternal antibodies (transferred from mother to baby near the end of pregnancy), which interfere with the vaccine. By their first birthday, most babies have lost the maternal antibodies and can be successfully vaccinated.

How effective is the vaccine?

It is estimated that the varicella vaccine will offer 70 to 90 per cent protection against chicken pox of any severity and over 95 per cent protection against severe varicella for at least seven to 10 years after vaccination.

Who is eligible to receive the publicly funded vaccine?

Children who were born on or after September 1, 2003 are eligible to get a single dose of the publicly funded vaccine.

In January 2005, the publicly funded vaccine will be available for susceptible five-year-old children (who have not had chicken pox). People with medical conditions that put them at increased risk for complications due to chicken pox will also be eligible :

  • children and adolescents given chronic salicylic acid therapy
  • people with cystic fibrosis
  • immunocompromised individuals - this should be determined on an individual basis. The vaccine (a live, attenuated vaccine) is recommended for some immunocompromised persons, but contraindicated for others. Please discuss this with your doctor.

Are there side effects from the vaccine?

Most reactions tend to be mild and include some soreness, redness, itching and/or a rash where the needle was given. A low-grade fever (approximately 38°C) may occur.

Some children may get a very mild case of chicken pox one or two weeks after they get the vaccine but are not likely to be contagious.

Severe reactions are rare.

Please report any side effects or severe vaccine reaction to your doctor/nurse practitioner or local public health unit.

Who should not get the vaccine?

Children should not receive the vaccine if they :

  • have allergies to the vaccine or any component of the vaccine
  • have already had chicken pox
  • had an anaphylactic reaction to a prior dose of the vaccine.

Special consideration is needed for children with weakened immune systems or those on medications to suppress their immune system.

Pregnant women should not be vaccinated.

You should always discuss the benefits and risks of any vaccine with your doctor/nurse practitioner or local public health unit.

When should I call my doctor/nurse practitioner?

Call your doctor/nurse practitioner or go to the nearest hospital emergency department if your child has any of the following symptoms within three days of getting the needle :

  • hives
  • swelling of the mouth and throat
  • trouble breathing, hoarseness or wheezing
  • high fever (over 40°C or 104°F)
  • convulsions or seizures
  • other serious reaction to the vaccine.

Who should I talk to if I have any questions?

For more information see your doctor/nurse practitioner or call your local public health unit.

How do I keep track of my child's immunizations?

After your child receives any immunization, make sure his/her personal immunization record (sometimes called the Yellow Card), is updated. Keep it in a safe place!

December 2004 / Cat # 7610-2142074

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